This invention relates generally to magnetic recording media such as magnetic thin film recording disks, and more particularly the invention relates to a magnetic recording media structure comprising a plurality of sputtered layers for achieving recording properties perpendicular to the plane of the media
The magnetic disk drive as used for data storage in computer systems comprises one or more disks having thin film magnetic layers on opposing surfaces for the recording of magnetic data as bits along concentric tracks. Typically, as shown in FIG. 1A, the disk comprises a substrate 4 of nickel phosphorous (NiP) or ceramic glass on which a plurality of layers are formed by sputtering in a low pressure inert gas atmosphere. The layers include a non-magnetic seedlayer 6, a non-magnetic underlayer 8 of either pure chromium (Cr) or a chrome alloy (CrX), covered by a magnetic layer 10 of a cobalt-(Co) based alloy. A protective layer 12 of sputtered carbon (C) is typically used on top of the magnetic layer and an organic lubricant 14 may be used on top of the protective layer.
The magnetic layer can be either longitudinally magnetized in the plane of the layer or perpendicularly magnetized perpendicular to the plane of the layer. For perpendicular recording, a magnetically soft layer 7, for example, NiFe, is often added to provide an image effect for the writing process. To achieve optimal perpendicular recording properties, the Co alloy magnetic layer has its easy axis magnetization aligned perpendicular to the plane of the disk. To achieve this, an underlayer such as close packed hexagonal (hcp) Ti or TiCr can be deposited to promote the growth of a hcp Co alloy perpendicular to the plane.
The present invention is directed to achieving an improved perpendicular magnetized magnetic layer through use of a reduced number of sputtered underlayers.
In accordance with the invention, a magnetic recording medium such as a magnetic disk comprises a substrate, an underlayer supported by the substrate with the underlayer preferably having a L10 lattice structure, and a magnetic layer comprising an alloy of cobalt deposited on the underlayer and having a magnetization which is perpendicular to the magnetic layer.
In a preferred embodiment of the invention, the underlayer is titanium aluminum (TiAl) and the substrate comprises nickel phosphorous (NiP) or ceramic glass. The magnetic layer comprises a cobalt alloy such as CoCrTaPt or CoCrPtB.
While a carbon overcoat and lubricant layer may be included in the recording medium structure, the need for a magnetic soft layer or a non-magnetic underlayer of chromium is obviated. In other embodiments, the L10 structure can be provided by alloys of other elements, and a disordered fcc structure can be employed, rather than the L10 lattice.
The invention and objects and features thereof will be more readily apparent from the following detailed description and appended claims when taken with the drawing.